1. Field of Invention
The present invention relates to a vehicle brake system for applying braking force to a plurality of wheels of a vehicle according to the operation of a brake pedal.
2. Description of Related Art
Electronically-controlled vehicle brake systems that controls the braking force by regulating, via a pressure source and a hydraulic pressure controller, the hydraulic pressure that is supplied to wheel cylinders, are available. By using such a vehicle brake system, it is possible to reduce the cost by reducing the number of control valves for sustaining pressure and control valves for reducing pressure to be installed. A vehicle brake system having a pair of linear control valves that are used for sustaining and reducing pressure, respectively, and having a hydraulic fluid passage that is separated by a communication valve into two passages that communicate with different wheel cylinders of the disc brakes that are installed for the respective wheels is described in Japanese Patent Application Publication No. 11-180294 (JP-A-11-180294).
However, when two passages are connected to each other with the communication valve interposed therebetween in the hydraulic fluid passage as described in JP-A-11-180294, the communication valve serves as a throttle orifice, and can cause the difference in the hydraulic pressure response between both sides of the communication valve when the pressure is changed.